The special counsel’s investigation has ensnared Mr. Flynn—and his son, Michael Flynn Jr. —on a number of fronts. Mr. Mueller is probing the alleged role played by Mr. Flynn and his son in a plan to forcibly remove a Muslim cleric living in the U.S. and deliver him to Turkey in return for millions of dollars, the Journal previously reported. Under the alleged proposal, Mr. Flynn and his son were to be paid as much as $15 million for delivering Fethullah Gulen to the Turkish government.

.. Mr. Mueller is also investigating what role, if any, Mr. Flynn or his son may have played in a private effort to obtain Hillary Clinton’s emails from Russian hackers